1. Field of the Invention
The present invention relates to a broadband wireless access (BWA) communication system, and more particularly to a system and a method for provisioning service flows which can be provided by a base station (BS).
2. Description of the Related Art
In the 4th generation (4G) communication system, which is the next generation communication system, research has been actively pursued to provide users with services having various Qualities of Services (QoSs) at high speed. Especially, in the current 4 G communication system, research has been actively pursued to develop a new type of communication system ensuring mobility and QoS and supporting high speed services in a Broadband Wireless Access (BWA) communication system such as a wireless Local Area Network (LAN) system and a wireless Metropolitan Area Network (MAN) system capable of supporting relatively high transmission speeds. As a representative of such new type communication systems, an Institute of Electrical and Electronics Engineers (IEEE) 802.16e communication system has been developed.
The IEEE 802.16e communication system is a system using an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) scheme for a physical channel of the WMAN system in order to support a broadband transmission network.
Hereinafter, a schematic structure of the conventional IEEE 802.16e communication system will be described with reference to the block diagram of FIG. 1.
The IEEE 802.16e communication system has a multi-cell structure and includes a cell 100, a cell 150, a base station (BS) 110 controlling the cell 100, a base station 140 controlling the cell 150, and a plurality of mobile stations (MSs) 111, 113, 130, 151, and 153. In addition, the BSs 110 and 140 transmit and receive signals to and from the MSs 111, 113, 130, 151, and 153 using the OFDM/OFDMA scheme.
The structure of the conventional IEEE 802.16e communication system is described with reference to FIG. 1, and, hereinafter, an MS initialization operation in the IEEE 802.16e communication system will be described with reference to the flow diagrams of FIGS. 2A and 2B.
When the power of the MS 200 is turned on, the MS performs a cell selection operation (step 211). In other words, the MS 200 monitors all frequency bands preset by the MS 200 so as to detect a reference signal (e.g., a pilot signal) having the strongest intensity, for example, the largest Carrier to Interference and Noise Ratio (CINR). Then, the MS 200 determines a base station (BS) having transmitted the pilot signal having the maximum CINR as a BS 250 currently covering the MS 200, and acquires system synchronization with the BS 250 by receiving a preamble of a downlink frame transmitted from the BS 250. Herein, if system synchronization between the MS 200 and the BS 250 is acquired, the MS 200 receives a DL-MAP message, a UL-MAP message, and an uplink channel descript (UCD) message transmitted from the BS 250. Thus, the MS 200 having received the DL-MAP message, the UL-MAP message, and the UCD message from the BS 250 can recognize time slots used for an initial ranging operation. The MS 200 randomly selects one predetermined time slot from among the time slots used for the initial raging operation and transmits a ranging-request (RNG-REQ) message for the initial ranging operation to the BS 250. Herein, the RNG-REQ message includes an initial ranging connection identifier (CID) and a media access control (MAC) address of the MS 200.
Upon receiving the RNG-REQ message from the MS 200, the BS 250 transmits a ranging-response (RNG-RSP) message, which is a response message for the RNG-REQ message, to the MS 200. If the MS 200 receives the RNG-RSP message from the BS 250, the MS 200 selects the BS 250 as a serving base station of the MS 200 and completes the cell selection operation.
If the cell selection operation is completed, the MS 200 performs entry into a network together with the BS 250. Hereinafter, a detailed description about the entry into the network will be given.
According to the completion of the cell selection operation, the MS 200 receives information about the BS 250 from the BS 250 through the DL-MAP message, the UL-MAP message, a downlink channel descript (DCD) message, a UCD message, and a neighbor advertisement (NBR-ADV) message (step 213). The MS 200 obtains a downlink synchronization with the BS 250 using the BS information received through the DL-MAP message, the UL-MAP message, the DCD message, the UCD message, and the NBR-ADV message (step 215). Thus, the MS 200 having obtained the downlink synchronization with the BS 250 transmits the RNG-REQ message to the BS 250 (step 217).
The BS 250 receives the RNG-REQ message from the MS 200 and allocates a basic connection identifier (basic CID) and a primary management connection identifier (CID) for the MS 200 by mapping with a medium access control (MAC) address included in the received RNG-REQ message (step 219).
The BS 250 allocates the basic CID and the primary management CID for the MS 200 and then transmits a ranging-response (RNG-RSP) message, which is a response message for the RNG-REQ message, to the MS 200 (step 221). Herein, the RNG-RSP message includes the allocated basic CID, the allocated primary management CID, and uplink synchronization information. The MS 200 acquires uplink synchronization with the BS and adjusts frequency of power by receiving the RNG-RSP message (step 223).
The MS 200 transmits a subscriber station basic capability request (SBC-REQ) message to the BS 250 (step 225). Herein, the SBC-REQ message is a medium access control (MAC) message transmitted by the MS 200 in order to negotiate for basic capability with the BS, and the SBC-REQ message includes information about a modulation and coding scheme which can be supported by the MS 200. The BS 250 receives the SBC-REQ message from the MS 200, checks the modulation and coding scheme, which can be supported by the MS 200, included in the SBC-REQ message, and then transmits a subscriber station basic capability response (SBC-RSP) message as a response message for the SBC-REQ message (step 227).
The MS 200 completes the negotiation for its basic capability (step 229) by receiving the SBC-RSP message. Then, the MS 200 transmits a privacy key management request (PKM-REQ) message to the BS 250 (step 231). Herein, the PKM-REQ message is a MAC message used for authentication of the MS and includes certificate information of the MS 200. The BS 250 having received the PKM-REQ message performs authentication with an authentication server (AS) using the certificate information of the MS 200 included in the PKM-REQ message. If it is determined that the MS 200 corresponds to an authenticated MS using the authentication information, the BS 250 transmits a privacy key management response (PKM-RSP) message to the MS 200 as a response message for the PKM-REQ message (step 233). Herein, the PKM-RSP message includes an authentication key (AK) and a traffic encryption key (TEK) allocated to the MS 200.
The MS 200 achieves the authentication of the MS 200 and obtains the traffic encryption key by receiving the PKM-RSP message (step 235). Then, the MS 200 transmits a registration request (REG-REQ) message to the BS 250 (step 237). The REG-REQ message includes MS registration information of the MS 200.
The BS 250 having received the REG-REQ message detects the MS registration information included in the REG-REQ message so as to register the MS 200 in the BS 250 and allocate a secondary management CID for the MS 200. The BS 250 having allocated the secondary management CID transmits a registration response (REG-RSP) message, which is a response message for the REG-REQ message, to the MS 200 (step 239). Herein, the REG-RSP message includes the allocated secondary management CID and the MS registration information.
The MS 200 completes its registration and obtains the secondary management CID by receiving the REG-RSP message (step 241). Thus, if the MS registration is completed, the MS 200 is allocated with three CIDs (i.e., the initial basic CID, the primary management CID, and the secondary management CID). Thus, if the MS 200 is completely registered, the BS 250 performs provisioning for service flows provided by the BS (step 260). A detailed description about the provisioning for the service flows is later given.
If the provisioning for the service flows is completed, that is, if an initialization operation of the MS 200 is completed, the MS 200 transits into a normal operation mode, an Internet protocol (IP) connection between the MS 200 and the BS 250 is achieved, and administration information is downloaded through the IP connection (step 271). Thereafter, the service flow is made between the MS 200 and the BS 250 (step 273). Herein, the service flow denotes a flow in which a MAC-service data unit (SDU) is transmitted and received through a connection having a predetermined QoS type. Since a transport CID must be allocated to the MS 200 when the MAC-SDU (i.e. traffic) is transmitted and received as described above, the MS is allocated with the transport CID in the connection of the service flow. Thus, if the connection of the service flow is achieved, a service is actually performed between the MS 200 and the BS 250 (step 275).
Hereinafter, detailed description about the provisioning for the service flow will be given.
If the registration of the MS 200 is completed, the BS 250 transmits a dynamic service addition request (DSA-REQ) message to the MS 200 (step 261). As the MS 200 receives the DSA-REQ message from the BS 250, the MS 200 transmits a dynamic service addition response (DSA-RSP) message, which is a response message for the DSA-REQ message (step 263). Herein, an operation of transmitting and receiving the DSA-REQ message or the DSA-RSP message is called a “DSA message transaction operation”. One DSA message transaction operation allows the setting of only one QoS type for a service flow. Accordingly, if there exists a plurality of QoS types supported by the BS 250, DSA message transaction operations corresponding to the number of the QoS types supported by the BS 250 must be performed with respect to the downlink or the uplink.
For example, the IEEE 802.16e communication system supports all four QoS types including an unsolicited granted service (UGS) type, a real time polling service type (rtPS) type, a non real time polling service (nrtPS) type, and a best effort (BE) type.
Therefore, if the BS 250 can support all four QoS types, the BS 250 performs service flow provisioning for the four QoS types through the DSA message transaction operations in the uplink or the downlink. In other words, the BS 250 performs four DSA message transaction operations in order to perform service flow provisioning for the four QoS types in the downlink. In addition, the BS 250 performs four DSA message transaction operations in order to perform service flow provisioning for the four QoS types in the uplink. As a result, the BS 250 performs the DSA message transaction operation eight times.
However, it is impossible for the IEEE 802.16e communication system to provide information about the number of service flows to be provisioned by the BS or information about a time point for the final provisioning of the BS. Accordingly, it is impossible for the MS to recognize the time point at which the final service flow provisioning of the BS is terminated, so that it is impossible for the MS to exactly detect the time point at which the MS transits into the normal operation mode. Thus, since the MS cannot accurately recognize the time point at which the MS enters into the normal operation mode, service quality provided by the MS is degraded.